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dm: adc: add simple ADC uclass implementation

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This commit adds:
- new uclass id: UCLASS_ADC
- new uclass driver: drivers/adc/adc-uclass.c

The new uclass's API allows for ADC operation on:
* single-channel with channel selection by a number
* multti-channel with channel selection by bit mask

ADC uclass's functions:
* single-channel:
  - adc_start_channel()        - start channel conversion
  - adc_channel_data()         - get conversion data
  - adc_channel_single_shot()  - start/get conversion data
* multi-channel:
  - adc_start_channels()       - start selected channels conversion
  - adc_channels_data()        - get conversion data
  - adc_channels_single_shot() - start/get conversion data for channels
                                 selected by bit mask
* general:
  - adc_stop()      - stop the conversion
  - adc_vdd_value() - positive reference Voltage value with polarity [uV]
  - adc_vss_value() - negative reference Voltage value with polarity [uV]
  - adc_data_mask() - conversion data bit mask

The device tree can provide below constraints/properties:
- vdd-polarity-negative: if true: Vdd = vdd-microvolts * (-1)
- vss-polarity-negative: if true: Vss = vss-microvolts * (-1)
- vdd-supply:            phandle to Vdd regulator's node
- vss-supply:            phandle to Vss regulator's node
And optional, checked only if the above corresponding, doesn't exist:
  - vdd-microvolts:      positive reference Voltage [uV]
  - vss-microvolts:      negative reference Voltage [uV]

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
This commit is contained in:
Przemyslaw Marczak
2015-10-27 13:08:00 +01:00
committed by Minkyu Kang
parent 7c816e24a4
commit 5decbf5300
8 changed files with 783 additions and 0 deletions
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62
doc/device-tree-bindings/adc/adc.txt Normal file
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ADC device binding
There are no mandatory properties for ADC. However, if Voltage info is required,
then there are two options:
- use microvolts constraint or
- use regulator phandle to enable/read supply's Voltage
Properties and constraints:
*optional and always checked, Voltage polarity info:
- vdd-polarity-negative: positive reference Voltage has a negative polarity
- vss-polarity-negative: negative reference Voltage has a negative polarity
Chose one option, for each supply (Vdd/Vss):
*optional and always checked, supply Voltage constants:
- vdd-supply: phandle to Vdd regulator's node
- vss-supply: phandle to Vss regulator's node
*optional and checked only if the above corresponding, doesn't exist:
- vdd-microvolts: positive reference Voltage value [uV]
- vss-microvolts: negative reference Voltage value [uV]
Example with constant 'Vdd' value:
adc@1000000 {
compatible = "some-adc";
reg = <0xaabb000 0x100>;
status = "enabled";
vdd-microvolts = <1800000>;
};
Example of supply phandle usage, for the ADC's VDD/VSS references as below:
_______ _______
|Sandbox| |Sandbox|
: PMIC : : ADC :
. . . .
| | (Vdd) | AIN0|-->
| BUCK2|-------|VDDref |
| (3.3V)| _|VSSref |
|_______| | |_______|
_|_
For the above PMIC, the node can be defined as follows:
sandbox_pmic {
compatible = "sandbox,pmic";
...
buck2: buck2 {
regulator-name = "SUPPLY_3.3V";
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
};
...
};
For the above ADC, the node can be defined as follows:
adc@0 {
compatible = "sandbox,adc";
vdd-supply = <&buck2>;
vss-microvolts = <0>;
};
The ADC uclass code, will enable the supply before start of the conversion,
but it will not configure the regulator settings.